This is a note to let you know that I've just added the patch titled
cifs: prevent data race in cifs_reconnect_tcon()
to the 6.2-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
cifs-prevent-data-race-in-cifs_reconnect_tcon.patch
and it can be found in the queue-6.2 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 9b1a97c7aa9103eaed0e2fde976931dbb03b6622
Author: Paulo Alcantara <pc@xxxxxxxxxxxxx>
Date: Tue Feb 28 19:01:55 2023 -0300
cifs: prevent data race in cifs_reconnect_tcon()
[ Upstream commit 1bcd548d935a33c6fc58331405eb1b82fd6150de ]
Make sure to get an up-to-date TCP_Server_Info::nr_targets value prior
to waiting the server to be reconnected in cifs_reconnect_tcon(). It
is set in cifs_tcp_ses_needs_reconnect() and protected by
TCP_Server_Info::srv_lock.
Create a new cifs_wait_for_server_reconnect() helper that can be used
by both SMB2+ and CIFS reconnect code.
Signed-off-by: Paulo Alcantara (SUSE) <pc@xxxxxxxxxxxxx>
Signed-off-by: Steve French <stfrench@xxxxxxxxxxxxx>
Stable-dep-of: bc962159e8e3 ("cifs: avoid race conditions with parallel reconnects")
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/fs/cifs/cifsproto.h b/fs/cifs/cifsproto.h
index e75184544ecb4..639df85dafd6c 100644
--- a/fs/cifs/cifsproto.h
+++ b/fs/cifs/cifsproto.h
@@ -697,5 +697,6 @@ static inline int cifs_create_options(struct cifs_sb_info *cifs_sb, int options)
struct super_block *cifs_get_tcon_super(struct cifs_tcon *tcon);
void cifs_put_tcon_super(struct super_block *sb);
+int cifs_wait_for_server_reconnect(struct TCP_Server_Info *server, bool retry);
#endif /* _CIFSPROTO_H */
diff --git a/fs/cifs/cifssmb.c b/fs/cifs/cifssmb.c
index 566e6a26b897c..5ca4a5383aaae 100644
--- a/fs/cifs/cifssmb.c
+++ b/fs/cifs/cifssmb.c
@@ -70,7 +70,6 @@ cifs_reconnect_tcon(struct cifs_tcon *tcon, int smb_command)
struct cifs_ses *ses;
struct TCP_Server_Info *server;
struct nls_table *nls_codepage;
- int retries;
/*
* SMBs NegProt, SessSetup, uLogoff do not have tcon yet so check for
@@ -98,45 +97,9 @@ cifs_reconnect_tcon(struct cifs_tcon *tcon, int smb_command)
}
spin_unlock(&tcon->tc_lock);
- retries = server->nr_targets;
-
- /*
- * Give demultiplex thread up to 10 seconds to each target available for
- * reconnect -- should be greater than cifs socket timeout which is 7
- * seconds.
- */
- while (server->tcpStatus == CifsNeedReconnect) {
- rc = wait_event_interruptible_timeout(server->response_q,
- (server->tcpStatus != CifsNeedReconnect),
- 10 * HZ);
- if (rc < 0) {
- cifs_dbg(FYI, "%s: aborting reconnect due to a received signal by the process\n",
- __func__);
- return -ERESTARTSYS;
- }
-
- /* are we still trying to reconnect? */
- spin_lock(&server->srv_lock);
- if (server->tcpStatus != CifsNeedReconnect) {
- spin_unlock(&server->srv_lock);
- break;
- }
- spin_unlock(&server->srv_lock);
-
- if (retries && --retries)
- continue;
-
- /*
- * on "soft" mounts we wait once. Hard mounts keep
- * retrying until process is killed or server comes
- * back on-line
- */
- if (!tcon->retry) {
- cifs_dbg(FYI, "gave up waiting on reconnect in smb_init\n");
- return -EHOSTDOWN;
- }
- retries = server->nr_targets;
- }
+ rc = cifs_wait_for_server_reconnect(server, tcon->retry);
+ if (rc)
+ return rc;
spin_lock(&ses->chan_lock);
if (!cifs_chan_needs_reconnect(ses, server) && !tcon->need_reconnect) {
diff --git a/fs/cifs/misc.c b/fs/cifs/misc.c
index 9f4486b705d5c..5542893ef03f7 100644
--- a/fs/cifs/misc.c
+++ b/fs/cifs/misc.c
@@ -1376,3 +1376,47 @@ int cifs_inval_name_dfs_link_error(const unsigned int xid,
return 0;
}
#endif
+
+int cifs_wait_for_server_reconnect(struct TCP_Server_Info *server, bool retry)
+{
+ int timeout = 10;
+ int rc;
+
+ spin_lock(&server->srv_lock);
+ if (server->tcpStatus != CifsNeedReconnect) {
+ spin_unlock(&server->srv_lock);
+ return 0;
+ }
+ timeout *= server->nr_targets;
+ spin_unlock(&server->srv_lock);
+
+ /*
+ * Give demultiplex thread up to 10 seconds to each target available for
+ * reconnect -- should be greater than cifs socket timeout which is 7
+ * seconds.
+ *
+ * On "soft" mounts we wait once. Hard mounts keep retrying until
+ * process is killed or server comes back on-line.
+ */
+ do {
+ rc = wait_event_interruptible_timeout(server->response_q,
+ (server->tcpStatus != CifsNeedReconnect),
+ timeout * HZ);
+ if (rc < 0) {
+ cifs_dbg(FYI, "%s: aborting reconnect due to received signal\n",
+ __func__);
+ return -ERESTARTSYS;
+ }
+
+ /* are we still trying to reconnect? */
+ spin_lock(&server->srv_lock);
+ if (server->tcpStatus != CifsNeedReconnect) {
+ spin_unlock(&server->srv_lock);
+ return 0;
+ }
+ spin_unlock(&server->srv_lock);
+ } while (retry);
+
+ cifs_dbg(FYI, "%s: gave up waiting on reconnect\n", __func__);
+ return -EHOSTDOWN;
+}
diff --git a/fs/cifs/smb2pdu.c b/fs/cifs/smb2pdu.c
index 6e6e44d8b4c79..83d04cd2f9df8 100644
--- a/fs/cifs/smb2pdu.c
+++ b/fs/cifs/smb2pdu.c
@@ -139,66 +139,6 @@ smb2_hdr_assemble(struct smb2_hdr *shdr, __le16 smb2_cmd,
return;
}
-static int wait_for_server_reconnect(struct TCP_Server_Info *server,
- __le16 smb2_command, bool retry)
-{
- int timeout = 10;
- int rc;
-
- spin_lock(&server->srv_lock);
- if (server->tcpStatus != CifsNeedReconnect) {
- spin_unlock(&server->srv_lock);
- return 0;
- }
- timeout *= server->nr_targets;
- spin_unlock(&server->srv_lock);
-
- /*
- * Return to caller for TREE_DISCONNECT and LOGOFF and CLOSE
- * here since they are implicitly done when session drops.
- */
- switch (smb2_command) {
- /*
- * BB Should we keep oplock break and add flush to exceptions?
- */
- case SMB2_TREE_DISCONNECT:
- case SMB2_CANCEL:
- case SMB2_CLOSE:
- case SMB2_OPLOCK_BREAK:
- return -EAGAIN;
- }
-
- /*
- * Give demultiplex thread up to 10 seconds to each target available for
- * reconnect -- should be greater than cifs socket timeout which is 7
- * seconds.
- *
- * On "soft" mounts we wait once. Hard mounts keep retrying until
- * process is killed or server comes back on-line.
- */
- do {
- rc = wait_event_interruptible_timeout(server->response_q,
- (server->tcpStatus != CifsNeedReconnect),
- timeout * HZ);
- if (rc < 0) {
- cifs_dbg(FYI, "%s: aborting reconnect due to received signal\n",
- __func__);
- return -ERESTARTSYS;
- }
-
- /* are we still trying to reconnect? */
- spin_lock(&server->srv_lock);
- if (server->tcpStatus != CifsNeedReconnect) {
- spin_unlock(&server->srv_lock);
- return 0;
- }
- spin_unlock(&server->srv_lock);
- } while (retry);
-
- cifs_dbg(FYI, "%s: gave up waiting on reconnect\n", __func__);
- return -EHOSTDOWN;
-}
-
static int
smb2_reconnect(__le16 smb2_command, struct cifs_tcon *tcon,
struct TCP_Server_Info *server)
@@ -239,7 +179,27 @@ smb2_reconnect(__le16 smb2_command, struct cifs_tcon *tcon,
(!tcon->ses->server) || !server)
return -EIO;
- rc = wait_for_server_reconnect(server, smb2_command, tcon->retry);
+ spin_lock(&server->srv_lock);
+ if (server->tcpStatus == CifsNeedReconnect) {
+ /*
+ * Return to caller for TREE_DISCONNECT and LOGOFF and CLOSE
+ * here since they are implicitly done when session drops.
+ */
+ switch (smb2_command) {
+ /*
+ * BB Should we keep oplock break and add flush to exceptions?
+ */
+ case SMB2_TREE_DISCONNECT:
+ case SMB2_CANCEL:
+ case SMB2_CLOSE:
+ case SMB2_OPLOCK_BREAK:
+ spin_unlock(&server->srv_lock);
+ return -EAGAIN;
+ }
+ }
+ spin_unlock(&server->srv_lock);
+
+ rc = cifs_wait_for_server_reconnect(server, tcon->retry);
if (rc)
return rc;
